應用有限元素方法分析吉他之振動-聲學特性

Finite Element Analysis for Guitar Vibro-Acoustic Characteristics and Coupled Physics Study

蘇柏安(Po-An Su)

指導教授 ： 蔡龍

共同指導教授 ： 羅鴻生(Hon-Seng Lo)

健行科技大學/工學院/機械工程所/碩士(2008年)

摘要

弦樂器吉他的構造內，含音箱、琴柄及弦…等各部份所組成的。本文應用計算機輔助工程設計程式Auto CAD及計算機輔助工程分析程式ANSYS，建立吉他零組、總成及系統之數學(包括幾何及物理) 模型。基於振動學及聲學流體之理論，以有限元素方法進行吉它整體及各部份組件之自由振動分析，包括共振共鳴頻率及模式型態等結構與流體動態特性之計算。其中零組件部份之弦為兩端固定邊界條件；琴柄為一端固定邊界條件；音箱內空邊界為固定邊界。總成部份例如木箱加空氣，木箱加柄，木箱加空氣加柄及系統（木箱加空氣加柄加弦）等試件皆用自由邊界設定而後計算。討論各組件結構與整體自由反應中的關連性質，為音樂演奏及聲音調校尋找出比較有效及快速的結構振動控制方法，並且可供吉他結構細部等最佳化設計之參考。

關鍵字

吉他 ； 聲彈耦合 ； 動態特徵

並列摘要

In the structure of the guitar, it is composed of the body, neck, strings, and so on. The purpose of the thesis reports on the applications of Auto CAD and the ANSYS computer packages to simulate the model of the above mentioned parts mathematically and physically, trying to utilize the finite element method to analyze the free vibration of the individual parts and whole body. Based on the theories of vibration and acoustics, in this research it includes the calculation of the resonant frequencies and corresponding mode shapes; the boundary condition for the strings and the body is fixed-fixed, while for the neck, it is set fixed at one end and free at the other. Finally, in order to find the physical connection between the whole body and those individual parts, in this paper we includes the calculations of the body-air, body-neck, and body-air-neck-strings with free-free boundary condition, hoping to find an efficient way to control the vibration among them and an optimal design of the guitar industry.

並列關鍵字

Guitar ； acoustic shells coupling ； dynamic feature

參考文獻

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